Grain tanks of combines commonly have an associated unloader conveyor operable for conveying grain from the grain tank to another location such as to a grain truck or wagon. An unloader conveyor typically includes an elongate, enclosed tubular housing containing a helical auger and is oriented horizontally or at a small acute angle to horizontal. The unloader conveyor is typically pivotally supported in cantilever relation by a lower end of an upstanding or vertical lower unloader conveyor section including an inlet opening disposed in or adjacent to the grain tank. The unloader conveyor is typically pivotable between a stored position extending along the combine, and a sidewardly extending unloading position. The unloader can be of any length, but will typically have a length sufficient to extend just beyond the end of a header of the combine. Grain tanks additionally typically include at least one grain tank conveyor including an auger adjacent to the bottom of the grain tank and extending into the inlet opening of the lower unloader conveyor for conveying grain into the unloader.
Use of an auger associated with an unloader conveyor often results in both vibration during operation of the unloader conveyor, as well as sliding and mixing of the crop or grain along the auger surface, possibly resulting in damage to the crop or grain and requiring increased power to convey the crop or grain along the unloader conveyor. In U.S. 2010/275563 A1 the unloader conveyor comprises a conveyor belt for transporting the grain from the grain tank to the grain truck, thereby avoiding some of the auger related disadvantages.
However, installing a conveyor belt inside the conveyor tube instead of an auger results in a reduction of the tube cross section available for transporting the crop, which may reduce the overall crop delivery rate of the harvester.
Thus, there is a need and a desire for a crop delivery system that can maintain high delivery rates while reducing vibration and the opportunity for crop or grain damage during delivery thereof.